Condensation of o, o-diesters of dithiophosphoric acid and aliphatic alcohols or mercaptans with higher aliphatic aldehydes



Patented Aug. 28, 1951 CONDENSATION OF 0,0-DIESTERS OF DI- THIOPHOSPHORIC ACID AND ALIPHATIC. 1 ALCOHOLS OR MERCAPTANS WITH HIGH- ER ALIPHATIC ALDEHYDES Edwin 0. Hook, Old Greenwich, Conn., and Philip H. Moss, Austin, Tex., assignors to American Cyanamid Company, New York, N. Y., a corporation of Maine No Drawing. Original application March 26, 1948, Serial No. 17,395. Divided and this application March 7,1950, Serial No. 148,278

2 Claims. (01; 260-461) .triesters of dithiophosphoric acid, and particularly to the production of esters of thi class which are soluble inhydrocarbon oils and possess antioxidant and anticorrosion properties therefor. Many of the esters of the invention-are also good insecticides.

This is a division of our copendingapplication Serial No. 17,395, filed March 26, 1948, wherein the esters are claimed as new compositions of matter. A novel method for the preparation of these esters is claimed herein, this method consisting essentially in the step of condensing together an 0,0-diester of dithiophosphoric acid, an aliphatic monohydric alcohol or mercaptan and a higher aliphatic aldehyde, as will hereinafter be more fully described.

The novel dithiophosphoric acid triesters of -.the invention are defined by the formula:

H S.C.X.R'

in which X is oxygen or sulfur, each of R and R is an ester forming radical, which term includes alkyl, cycloalkyl and ar lalkyl radicals as well as substituted aliphatic radicals and aromatic radicals such as a phenyl or substituted phenyl radical, R is an aliphatic radical and R is hydrogen or an aliphatic radical. It will thus be seen that the compounds are 0,0-dialkyl-, diarylor mixed alkyl-aryl-S-allwlidene triesters of dithiophosphoric acid.

Most of the novel compounds of the invention are light to dark colored liquids which are soluble in lubricating oil and in benzene, toluene, kerosene, light mineral oils and other non-polar solvents. They are very effective in preventing the oxidation of mineral oils, such as mineral lubricating oils, and in preventing or reducing the corrosion of bearings lubricated by these oils, when used in amounts of 0.1-5% or more in weight, based on the weight of the: oil. They also possess the property of improving the corrosion inhibition of other lubricating oil additives such as polyvalent metal salts of diesters of dithiophosphoric acid, notably barium dialkyldithiophosphates in'which the alkyl radicals contain from 5-10 or more carbon atoms, calcium petroleum sulfonate and other organic oil-soluble sulfonates, alkyl phenol sulfides and their metal salts such as barium 2,4-dialkyl phenol mono-=- sulfide and the like. Many of these esters also z possess insecticidal properties and may be used as pest controls in the form of solutions in kero= sene or other mineral hydrocarbon solvents, or as aqueous emulsions or as mists or vapors.

We have discovered that compounds of the type defined by the above formula in which X is either oxygen or sulfur can be prepared by condensing an aliphatic monohydric alcohol or an aliphatic monomercaptan with an 0,0-diester of dithiophosphoric acid and with an alkanal" such as acetaldehyde, propionaldehyde, butyraldehyde or other higher aliphatic aldehyde. This condensation takes place when the reagents are mixed together at ordinary room temperature or at elevated temperatures up to C. or higher; however, the condensation reaction is exothermic and positive cooling of the reaction mixture is frequently advisable. The reaction is illustrated by the following equation:

in which X, R, R R and R are as defined above.

Any 0,0-dialiphatic dithiophosphoric acid diester including the dicycloalkyl dithiophosphoric acid esters or any 0,0-diaryl dithiophosphoric acid ester or any mixed 0,0-diester of dithiophosphoric acid may be used in practicing the process of our invention and in producing the novel products thereof. When compounds having a relatively high percentage of combined phosphorus and sulfur are desired, as in the production of lubricating oil antioxidants having a high activity at relatively low temperatures, it is preferable to employ an 0,0-dialkyl dithiophosphoric acid in which the alkyl groups are of relatively low molecular weight, such as methyl, ethyl, propyl or butyl radicals. Dialkyl dithiophosphoricacids of higher molecular weight may of course be employed, such as diamyl, di-n-hexyl, dicyclohexyl or dioctyl di-= thiophosphoric acids, as well as the didecyl, didodecyl, ditetradecyl or dioctadecyl dithiophosphoric acids. The 0,0-diaryl dithiophosphoric acids may frequently be used to advantage, as in the production of lubricating oil additives having a high degree-of heat stability wherein the 0,0-di-phenyl-, 0,0-di-alkylphenyl-, and 0,0-di-naphthyl dithiophosphoric acids may be employed. Still other diaryl dithiophosphoric acids may be used in the production of compounds for other purposes; thus, for example, in the production of insecticides r-andjungicides the use of 0,0-di-chlorphenyl or di-bromphenyi dithiophosphoric acids in accordance with the process of the invention is frequently advantageous. It will be understood {that .m xed 0,0-dithiophosphoric acid diesters-may also be employed, as where a mixed= alkylphenyl dithiophosphoric acid is used to combine the 011- solubilizing properties of .an aliphatic radical with the heat-stabilizing landysludgeeinhibiting properties of the phenolic -and;particularly. lthe alkylphenyl derivatives in a lubricating oil.

Any aliphatic monohydric. alcohol or n c emercaptan may be used inrthelqoiidensationlgf an 0,0-diester of dithiophosphoric acid withan alcohol or mercaptan and a higher aliphatic aldehyde. Miphatic monohydric alcohols-which may be used include the saturated aliranols such as "ethanol, THEthEDOL- BUIKHDT touandgindiifiih octadecanol, and leiilh'el". the .straightechain pr branched-chain normal, secondary .LDI' tertiary alcohols may "be-used. 1The;:.corresponding;;mercaptans of ll.'8'or more carbonaatomsimayalso be employed, or*mixturesrofcalcohols-land mercapta-ns may be used. iisimilarlmiany higher aliphatic monoaldehyde smay :be zemployed, typical examples being acetaldehydc;:butyraidehyde, isobutyraldehyde; :vaIeraIdehyde; hexaldehyde, octanaldehyde; :myristic zv aldehyde. stearic aldehyde, or "in :general any :.;aliphatic.-. aldehyde of 2 to 18 carbon 'atoms inclusive.

- As is noted above, the-condensaticn:between the '0,0-dithiophosphoricaacididiestersi. andcthe monohydric or polyhydric aliphatic :ialcoholor mercaptan can" be 'carried :o'utsimplyby=-mixing these two reagentswith thealdehyde. It :is unnecessary to maintain;any particulanratio:of reacting ingredients, as the three reagents condense in equimolecular ratios; in fact it is {frequently convenient to maintain an excess of alcohol or:;-mecaptan present the reaction to function -.as a "diluent. Other anon-reactive diluents :such as volatile hydrocarbons of the type of benzene, toluene, solvent naphtha and the like may be used if desired. The condensation" product is 'easily recovered trom :t-he reaction mixture in a purified form by washing-with water or a dilute aqueous sodium: carbonate solution, or both, followed :b cheating to Qil-IOOW C.

at reduced pressure'to stripoff volatile impurities.

" The novel products of the presentinvention are preferably used"-in*1uhricating oils -in-arelatively small quantities 'which may vary' from about 0.1% up to about1.45%- or -greater;=depending on the *particular oil-and- 'on: the :degree of protection desired therein. In: automobile engine lubricating oils; quantities on thezorder of 0.2% to 2-3%-areusually* incorporated-unto the oil. Our'novel antioxidants are: compatible with all of the commonly used detergents, stabilizers, sludge-inhibitors and *other ingredients of compounded 'oils and maybe-used:inconjunction with smaller orlarger quantities "ofaliphatic-.- or

aromatic sulfonates such as calcium.:petrcnate, alkyl phenol sulfides such as p p dibutyl diarnylor dio'ctyl 1311613101 "HIOHO -RUE POlYSUlfidBS phenol monoor polysulfidesvand. their metal salts and metal salts of oxygen 'omsulfun-icontaining acids of phosphor-usesuchzas those described in U. S." 'Patents--Noacx2 3fi4s284 and 2,228,658 and Reissue 22,829. Theseanda other A mixture of 61 grams (0.23 mol) of di-n- ;prgpyldithiophosphoric acid and 46 grams (1.0 mol) .of.ethanol,was prepared and 14 grams (0.32 -:mol)-ofsacetaldehyde was added with agitation and cooling. The mixture was then allowed to stand overnight after which the reaction product was washed well with waterand stripped of volatilesby heating under reduced pressure Loii' a steam bath. Theproduct weighed-ddlgramsland was a thin, nearly co1o'rless* 1iquid which jwas foundbyanalysis to contain24-.1 sulfurafid 1 3% phosphorus. It was the Q O-rii n -p ropyl- S-ethoxyethylidenedithiophosphate.'

. Encample 2 Twenty-two grams (0.31-mol) ofbutyra-ldehyde was added to a-mixture ofBigrarns-('0.25n1ol)mof di-n-propyldith-iophosphpric acid and 46 grams (1.0 mol) of'ethanolandthe-miiture was agitated for two hours at room temperature and-thenl-al lowed-to stand overnight. "The product-Was washed with water and then with dilute sodium carbonate solution; and was heated o'n a steam bath at reduced pressure. There was obtained so grams of a Right-colored liquid which was easily soluble in lubricating"-oili -It was the 0,0-di-n-propy1-S-ethgxybutylidenedithiophospat c.

aamrl Following the procedure described in the previous example, 14-grams of acetaldehyde was added to a mixtureiof 54 grams (0.25 mol) of ldi hr d jwehe nh r a ar cilandfla ams-$ mo .9 .ta t a nbu r mcrqapian and. hin ands r ppinath re wa ro ipc fi' .ODmdifihi a t.- bu y c osph iaa li -ador i uidy .1 seawee 27.5%;0f sulfur ,and19.2% phospho rus.

" 1 samplers! in which X is a member of the group consisting of oxygen and sulfur, each of R and R is a member of the group consisting of alkyl and aromatic radicals, R is an alkyl radical and R is a member of the group consisting of hydrogen and alkyl radicals which comprises condensing together an 0,0-diester of dithiophosphoric acid of the formula in which R and R are as defined above, an aidehyde of the formula R .CHz.CHO

in which R is as defined above, and a member of the group consisting of aliphatic monohydric alcohols and aliphatic monomercaptans.

2. A method of producing S-ethylidene alkyl ether and thio-ether triesters of dithiophosphoric acid of the formula 6 RO\ /S a in which X is a member of the group consisting of oxygen and sulfur, each of R and R is a member of the group consisting of alkyland aromatic radicals and R is an alkyl radical which comprises condensing together an 0,0-diester of dithiophosphoric acid of the formula P 12 0 \SH in which R and R are as defined above, a member of the group consisting of aliphatic monohydric alcohols and aliphatic monomercaptans, and acetaldehyde.

EDWIN O. HOOK. PHILIP H. MOSS.

No references'cited. 

1. A METHOD OF PRODUCING S-ALKYLIDENE ALKYL ETHER AND THIOETHER TRIESTERS OF DITHIOPHOSPHORIC ACID OF THE FORMULA 